Adding --missing-strategy option for local predictions
Adding --missing-strategy flag in prediction, batch_prediction and evaluation args
Bug fixing in evaluations with proportional missing and tests
Adding --older-than and --newer-than options to --delete
Changing prediction info format to allow including fields information in brief format
Typos in comments
Combining tag and date selectors in delete syntax
Adding --multi-dataset flag to generate multi-datasets from lists of datasets
Adding --multi-dataset-attributes and improvements

Adding the dataset-attributes and multi-dataset-attributes prepared for
new generated datasets and field-map assignation in multi-datasets.

Doc changes and comment improvements
Changing related minor bindings version to 1.2.2
Adding files for testing proportional missing strategy
Bug fixing: max_categories user_metadata and objective field
Updating version to 1.5.1
Adding tests for max_categories user_metadata